1. Technical Field
The present invention relates generally to an improved data processing system, and in particular to a method, system, and computer product for performance monitoring in a data processing system. Still more particularly, the present invention provides a method, system, and computer product for monitoring input/output (I/O) performance without using the remote input/output (RIO) cables.
2. Description of Related Art
A multiprocessor data processing system is a data processing system that contains multiple central processing units. This type of system allows for logical partitioning in which a single multiprocessor data partitioning in which a single multiprocessor data processing system may run as if the system were two or more independent systems. In such a system, each logical partition represents a division of resources in the system and operates as an independent logical system. Each of these partitions is logical because the division of resources may be physical or virtual. For example, a multiprocessor data processing system may be partitioned into multiple independent servers, in which each partition has its own processors, main storage, and input/output devices.
Many systems include multiple remote input/output (RIO) subsystems in which each subsystem includes a bridge or some other interface to connect the subsystem with other portions of the data processing system through a primary or main input/output hub. Each of these remote I/O subsystems is also referred to as a “RIO drawer”. Each of these RIO drawers may include peripheral components, such as, for example, hard disk drives, tape drives, or graphics adapters.
RIO drawers are typically physically separated from the processors and memory components of the computer. The RIO drawers and their components are connected to the main computer using RIO network cables which allow the I/O devices contained within the RIO drawers to function with the remainder of the computer as if they were on the system bus.
Performance monitoring is often used in optimizing the performance of a system. A performance monitor is generally regarded as a facility incorporated into a processor to assist in analyzing selected characteristics of a system by determining a machine's state at a particular point in time. Some systems, such as the IBM eServer pSeries Regatta 690 and the IBM eServer pSeries and iSeries Squadrons systems, products of International Business Machines Corporation in Armonk, N.Y., use RIO links to connect the central electronics complex (CEC) to a host of I/O devices. These systems do not have JTAG access to the RIO drawers, and thus these RIO links provide the only communication paths from the processors in the CEC to the I/O drawers. Consequently, all performance monitoring commands must go through the RIO cables. However, sending performance monitoring commands through the RIO cables adds additional traffic to the RIO cables and can affect system performance.
Therefore, it would be advantageous to have a non-invasive method for monitoring I/O performance without using the RIO bus.